thanks for the info! I will check and I did find that it was an option. Strange. I figured it would be standard with the Levinson system.
I don't know if it was standard, but you can find out easy enough.
1. Remove glove box. It just unsnaps from the bottom.
2. Remove 5 (or 6?) screws around plastic glove box frame and remove. Plastic clips on the back.
3. Look to the right of the CD changer in the cavity below the A pillar.
If you have it there will be a box labelled XM, with a big long antenna wire all wadded up in there.
IIRC XM was a dealer option so it's probably hit or miss.